The invention herein concerns an add-on communication unit suitable to be added on to a main electrical appliance with separable power contacts, particularly a motor-starter appliance of the kind comprising an on-off control electro-magnet, a device for protection against electrical faults and a manual on-off control component.
In the known appliances of this type, particularly in the one described in document WO 01/27 958, an add-on communication unit can be added. This unit comprises a housing mounted frontally onto or into the main appliance. Moreover, we know that the add-on signalling units habitually associated with the circuit-breakers comprise at least one switch component and/or an electronic processing circuit able to communicate with the main appliance via mechanical dialogue components and/or electrical connection components.
The known add-on communication units do not enable a simple way of connecting to the main appliance either a classic control cable or a bus cablexe2x80x94in particular specific to a field busxe2x80x94, to assuring a link for signalling and control associated with the main appliance. Furthermore, they do not enable re-distributing to the main appliance the commands conveyed via such a link.
The purpose of this invention is to remedy this disadvantage.
According to the invention, the housing of the add-on unit presents, on its front face:
some first connections with an intake-output function, suitable for the connection of communication conductors, particularly bus conductors, assuring the link with an external device for controlling and monitoring the main appliance,
some second connections, with an output function, suitable for the connection of conductors to link with the control input terminals of the main appliance.
The connectors for linking the add-on unit with the exterior and those for re-distributing the control signals to the main appliance are assembled on the front face of the add-on unit; the other walls of the add-on unit are thus available for other functions, namely the functions of guiding the unit into the main housing, and electrical connection and mechanical dialogue with the main appliance. The assembly formed by the main appliance plus the add-on unit can then be designed of reduced size.
The first connections can be pins assembled in a connector situated on the front of the housing of the add-on unit, and composed of input pins (with the function of commanding the main appliance) and output pins (with the function of signalling the status of the main appliance). The first connections can include supply connections, particularly for an electronic processing circuit situated in the add-on unit or a reversing component.
The second connections are advantageously three in number, two connections being allocated to the appliance on-off signal and the third connection to a signal of reversal of the operating direction of the appliance.
The add-on unit can comprise at the rear at least one switching component designed to cooperate mechanically with a leading mechanical component situated in the main appliance and whose movement reflects a change in status of that appliance.